Vitamin D insufficiency is associated with enhanced monocyte thromboinflammation in obesity

Obesity is characterized by chronic low-grade inflammation and increased thrombotic risk. Vitamin D deficiency, common in obesity, may contribute to inflammatory and pro-coagulant responses. We investigated the influence of vitamin D on thromboinflammatory responses in obesity. Serum vitamin D, TF expression in monocytes, neutrophils and extracellular vesicles (EVs), and plasma inflammation, coagulation, and fibrinolytic markers were evaluated in obese individuals stratified by vitamin D status (<30 or ≥30 ng/mL) and eutrophic subjects. Procedures were approved by the IRB (UFJF 5.736.117). Vitamin D insufficiency was associated with increased TF expression in circulating monocytes. Circulating EVs (AnnV⁺CD63⁺) were characterized by flow cytometry regarding their cell source and TF expression. Vitamin D-insufficient obese individuals exhibited higher concentrations of TF⁺ EVs. To identify circulating factors contributing to monocytic TF expression, eutrophic whole blood was reconstituted with plasma from obese subjects in vitamin D insufficiency, with or without the LPS chelator polymyxin B, EV depletion, or vitamin D supplementation. Obese plasma induced higher monocytic TF expression, which was attenuated by polymyxin B, EV depletion, and vitamin D supplementation, indicating that LPS and circulating EVs contribute to obesity-associated monocytic TF expression, while vitamin D supplementation attenuates this response. Consistently, obesity-derived EVs also induced TF expression and a trend toward increased IL-1β secretion (p=0.0574) in eutrophic monocytes. Finally, monocytes from obese and eutrophic individuals were stimulated with LPS or leptin with or without Vitamin D treatment, which attenuated LPS- and leptin-induced TF and IL-1β secretion by obese monocytes. These findings implicate vitamin D insufficiency and microbial translocation with obesity-related thromboinflammation and support a role for vitamin D in modulating monocytic TF and pro-coagulant EVs.